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Acinetobacter baumannii has emerged as one of the dominant nosocomial human pathogens associated with high morbidity and mortality globally. Increased incidences of carbapenem-resistant A. baumannii (CRAB) have resulted in an enormous socioeconomic burden on health-care systems. Here, we report the genotypic and phenotypic characterization of novel ST1816 and ST128 variants in A. baumannii strains belonging to International clone II (GC2) with capsule types KL1:OCL8 and KL3:OCL1d from India. Sequence analysis revealed the presence of diverse virulome and resistome in these clinical strains, in addition to islands, prophages, and resistance genes. The oxacillinase bla OXA–23 detected in the genomic island also highlighted the coexistence of bla OXA–66 / bla OXA–98 , bla ADC73 / bla ADC–3 , and bla TEM–1D in their mobile scaffolds, which is alarming. Together with these resistance-determining enzymes, multidrug efflux transporters also harbored substitutions, with increased expression in CRAB strains. The hotspot mutations in colistin resistance-conferring operons, PmrAB, LpxACD, and AdeRS, were additionally confirmed. Phenotype microarray analysis indicated that multidrug-resistant strains A. baumannii DR2 and A. baumannii AB067 preferred a range of antimicrobial compounds as their substrates relative to the other. To our knowledge, this is the first comprehensive report on the characterization of A. baumannii variants ST1816 and ST128, with different genetic makeup and genome organization. The occurrence of CRAB infections worldwide is a severe threat to available limited therapeutic options; hence, continued surveillance to monitor the emergence and dissemination of such novel ST variants in A. baumannii is imperative. [ABSTRACT FROM AUTHOR]

Quinolones are one of the most important classes of antibacterials available for the treatment of infectious diseases in humans. However, there is a growing concern about bacterial resistance to antimicrobials including quinolones. The spread of antibiotic-resistant bacteria in the aquatic environment has been recognized as a growing threat to public health and hospitals appear to be a major contributor to this. The objective of this study was to investigate the prevalence of quinolone resistance in Escherichia coli from selected water bodies receiving direct hospital effluents in Kerala, India. Standard disc diffusion and E-test were used for antibiotic susceptibility testing. As antibiotic resistance can develop in bacterial isolates by different means, EtBr Agar Cartwheel method was used to detect the efflux pump activity and presence of resistant genes was detected by PCR. The mechanism of transfer of plasmid mediated resistance was confirmed by conjugation experiments. A total of 209 multidrug-resistant Escherichia coli were isolated from different hospital effluent discharge sites and aquaculture farms located in their vicinity. Among them, qnrB was found to be most prevalent followed by qnrS, OqxAB, qnrA and aac (6')-Ib-cr. The results suggested that the antibiotics present at sub-inhibitory concentrations in direct hospital effluents increases the selection pressure impacting the cell function of even normal microorganisms in the aquatic environment to change the genetic expression of virulence factors or acquire resistance genes by different transfer mechanisms, posing a serious threat to public health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Polluted waters are an important reservoir for antibiotic resistance genes and multidrug-resistant bacteria. This report describes the microbial community, antibiotic resistance genes, and the genetic profile of extended spectrum β-lactamase strains isolated from rivers at, Pune, India. ESBL-producing bacteria isolated from diverse river water catchments running through Pune City were characterized for their antibiotic resistance. The microbial community and types of genes which confer antibiotic resistance were identified followed by the isolation of antibiotic-resistant bacteria on selective media and their genome analysis. Four representative isolates were sequenced using next generation sequencing for genomic analysis. They were identified as Pseudomonas aeruginosa, Escherichia coli, and two isolates were Enterobacter cloacae. The genes associated with the multidrug efflux pumps, such as tolC, macA, macB, adeL, and rosB, were detected in the isolates. As MacAB-TolC is an ABC type efflux pump responsible for conferring resistance in bacteria to several antibiotics, potential efflux pump inhibitors were identified by molecular docking. The homology model of their MacB protein with that from Escherichia coli K12 demonstrated structural changes in different motifs of MacB. Molecular docking of reported efflux pump inhibitors revealed the highest binding affinity of compound MC207-110 against MacB. It also details the potential efflux pump inhibitors that can serve as possible drug targets in drug development and discovery.